Abstract: A phase sensitive optical time domain reflectometry based distributed acoustic sensing system eliminating a degradation in a sensing performance encountered due to a finite extinction ratio of optical elements used to generate optical pulses is provided. A classical Optical Time Domain Reflectometer (OTDR) concept and a phase-OTDR concept are merged to generate an optic pulse for an interrogation with commercially available optic modulators. Characteristics of a light inside a fiber optic cable carry properties of both classical OTDR and phase-OTDR systems. The proposed solution does not require any modifications in a receiver part of the phase-OTDR systems and the proposed solution is used for any type of phase-OTDR system structure.

Abstract: A method for characterising high aspect ratio (“HAR”) structures etched in a substrate includes, for at least one structure, an interferometric measurement step, carried out with a low-coherence interferometer positioned on a top surface of the substrate, for measuring with a measurement beam, at least one depth data relating to a depth of the HAR structure, and a first adjusting step for adjusting a diameter, at the top surface, of the measurement beam according to at least one top critical dimension (“top-CD”) data relating to a width of the HAR structure.

Abstract: A method and system implementing the method for characterising structures etched in a substrate, such as a wafer, includes at least one structure etched in the substrate, an imaging step including the following steps: capturing, with an imaging device positioned on the top surface of the substrate, at least one image of a top surface of the substrate, and measuring a first data relating to the structure from at least one captured image, at least one interferometric measurement step, carried out with a low-coherence interferometer positioned on the top surface, for measuring with a measurement beam positioned on the structure, at least one depth data relating to a depth of the structure; and a first adjusting step for adjusting the measurement beam according to the first data.

Abstract: A method for determining properties of a sample (12) by ellipsometry includes positioning the sample (12) in an ellipsometer (10) so that a surface normal (n) of a measurement region of the sample surface is tilted relative to a reference axis (z) of the ellipsometer (10) and measuring a Mueller matrix for the measurement region. The method then includes creating an equation system by equating the measured Mueller matrix and a matrix product formed of: a rotation matrix about an input rotation angle (?); an isotropic Mueller matrix in normalized NCS form and a rotation matrix about an output rotation angle (??). The method then solves the equation system for the parameters representing the sample properties to be determined. The input rotation angle (?) and the output rotation angle (??) are set as parameters independent of one another when setting up the equation system.

Abstract: Stationary devices employing quadrature phase analysis light scattering are provided, to aid in the determination of the magnitude and polarity of electrophoretic mobility and zeta potential of particles in colloids. The devices use an optical quadrature interferometer with an electrophoresis sample chamber containing sample particles undergoing electrophoresis, the optical quadrature interferometer being configured to generate a quadrature signal. The phase of the quadrature signal may be analyzed at the frequency of the sample chamber electric field to estimate displacements and directions of the particles. The estimates can be used to determine a central value of the magnitude of the electrophoretic mobility, as well as its polarity. Particles having low electrophoretic mobility, or that may be adversely affected by high electric fields, can be analyzed, and constraints on vibration and light source coherence length may be relaxed. A phase modulator or frequency shifter is not required.

Abstract: Disclosed are methods and systems correcting bulk-motion artifacts in phase-based functional OCT images. The disclosed methods and systems are based on the use of the standard deviation of the phase shift signal present in phase-based OCT imaging. When applied with functional OCT techniques such as OCT angiography, Doppler OCT, and OCT elastography, the disclosed methods provide improved image quality and decreased computational cost compared to other methods of bulk motion compensation.

Abstract: A measurement system and an inspection method for detecting a defective bonding interface in a sample substrate including at least one element disposed on a support. The method comprises: placing the sample substrate in the measurement system, establishing an inclination map of the exposed surface, analyzing the inclination map and identifying a zone or zones of the exposed surface whose inclinations deviate by more than a given threshold from the inclination of the reference surface; and detecting the presence of a defective bond between the element and the support, depending on the result of the analysis of the inclination map.

Abstract: An optical system may include a light source to provide a beam of light. The optical system may include a reflector to receive and redirect the beam of light. The optical system may include a light gate having an opening to permit the beam of light, from the reflector, to travel through the opening. The optical system may include a light sensor to receive a portion of the beam of light after the beam of light travels through the opening, and convert the portion of the beam of light to a signal. The optical system may include a processing device to determine whether a notch of a wafer is in an allowable position based on the signal.

Abstract: The present disclosure discloses methods and systems for detecting an IR security mark in a document based on known color information and halftone frequency information. The method includes receiving a document from a user, including an IR security mark. Then, location information, color information and halftone frequency information are received from the user. The document is scanned. Based on the color information and the location information, the IR security mark is extracted from the scanned document. After this, halftone frequency information of the extracted IR security mark is verified. Based on the verification, text in the extracted IR security mark is identified and is then compared with one or more pre-stored IR security marks to ascertain whether the IR security mark in the document is an authentic security mark.

Abstract: A measurement system includes an atomizer, an impactor, a particle counter, and a discharge reservoir. The atomizer has a liquid intake port and a gas intake port configured to aerosolize a liquid received at the liquid intake port. The impactor has an inlet coupled to the atomizer and has a first output port and a second output port. The impactor is configured to separate droplets wherein those droplets smaller than a selected cut point are directed to the first output port and those droplets larger than the selected cut point are directed to the second output port. The particle counter is coupled to the first output port and is configured to count particles larger than at least one particle size cut point. The discharge reservoir is coupled to the second output port.

Abstract: The interferometer 10 according to this disclosure includes: a first optical component 12 that splits each of the P polarization component and the S polarization component of the light to be measured into the first optical path R1 and the second optical path R2 and combines the light to be measured; a second optical component 13 placed in the first optical path; a third optical component 14 that splits the light to be measured into the P polarization component and the S polarization component; and a P polarization detector 11a and an S polarization detector 11b that respectively detect the P polarization component and the S polarization component split by the third optical component, wherein the second optical component has an optical surface that changes the propagation direction of the light to be measured and gives a phase difference between the P polarization component and the S polarization component.

Abstract: A light source device includes a semiconductor laser that has a first end surface and a second end surface parallel to each other and forming a first resonator, and an optical system that is disposed on an optical path of laser light emitted from the semiconductor laser, that forms a second resonator with the second end surface of the semiconductor laser, and that has a reflection characteristic in which a reflectance with respect to light having a previously specified wavelength width centered at a specified center wavelength of the semiconductor laser is higher than the reflectance of the first end surface.

Abstract: A method for identifying three entangled photons includes generating a set of first, second, and third entangled photons correlated in time and interfering the first and second entangled photons based on a difference between a first optical path from an output of an optical source that generates the first entangled photon to a first optical input to an interferometric beam splitter and a second optical path from an output of the optical source that generates the second entangled photon to a second input of the interferometric beam splitter. A first electrical signal is generated in response to detection of a first photon generated by the interfering of the first and second entangled photons. A second electrical signal is generated in response to detection of a second photon generated by the interfering of the first and second entangled photons. A third electrical signal is generated in response to detection of the third entangled photon.

Abstract: An apparatus includes a photonic integrated circuit, which includes at least one splitter configured to split at least one input beam into multiple input beamlets and multiple phase modulators configured to phase-shift at least some of the input beamlets. The apparatus also includes an array of optical amplifiers configured to amplify the phase-shifted input beamlets and generate amplified beamlets. The apparatus further incudes a beam combiner configured to combine the amplified beamlets and generate an output beam. In addition, the apparatus includes a controller configured to control the phase modulators in order to adjust phasing of the phase-shifted input beamlets.

Abstract: A system includes a memory, and at least one processing device, operatively coupled to the memory, to facilitate an etch recipe development process by performing operations including obtaining, from an optical detector, first material thickness data for a first material and second material thickness data for a second material resulting from an iteration of an etch process using an etch recipe. The first material is located at a first reflectometry measurement point and the second material is located at a second reflectometry measurement point different from the first reflectometry measurement point. The operations further include determining one or more etch parameters based on at least the first material thickness data and the second material thickness data.

Abstract: Methods for characterizing the surface shapes of optical elements include the following steps: carrying out, in an interferometric test arrangement, at least a first interferogram measurement on the optical element by superimposing a test wave, which has been generated by diffraction of electromagnetic radiation on a diffractive element and has been reflected at the optical element, carrying out at least one additional interferogram measurement on in each case one calibrating mirror for determining calibration corrections, and determining the deviation from the target shape of the optical element based on the first interferogram measurement carried out on the optical element and the determined calibration corrections. At least two interferogram measurements are carried out for the at least one calibrating mirror, which differ from one another with regard to the polarization state of the electromagnetic radiation.

Abstract: Holographic Video Microscopy analysis of non-spherical particles is disclosed herein. Properties of the particles are determined by application of light scattering theory to holography data. Effective sphere theory is applied to provide information regarding the reflective index of a sphere that includes a target particle. Known particles may be co-dispersed with unknown particles in a medium and the holographic video microscopy is used to determine properties, such as porosity, of the unknown particles.

Abstract: Embodiments of the disclosure are drawn to apparatuses and methods for a rotating optical reflector. Optical systems may have a limited field of view, and so in order to expand the area that the optical system collects data from, the field of view of the optical system may be scanned across a target area. The present disclosure is directed to a rotating optical reflector, which includes a transmissive layer which refracts light onto a reflective layer, which has a normal which is not parallel to the axis about which the optical reflector is rotated. The optical reflector may be both statically and dynamically balanced, which may allow an increased size of the optical reflector, which in turn may increase the aperture of an optical system (e.g., a lidar system) using the rotating optical reflector.

Abstract: A system includes a first optical unit that emits light to a measurement target object and receives first interference light incident from the measurement target object, a second optical unit that emits the light to a reference object configured to have a constant optical path length with respect to a temperature fluctuation and receives second interference light incident from the reference object, a spectroscope connected to the first optical unit and the second optical unit and receives the first interference light and the second interference light to be incident, and a control unit connected to the spectroscope, and the control unit calculates a fluctuation rate of a measurement optical path length with respect to a reference optical path length under a predetermined temperature environment on the basis of the optical path length of the reference object calculated on the basis of the second interference light incident on the spectroscope under the predetermined temperature environment, and the reference op

Abstract: An apparatus for measurement of Thomson scattering signals from a plasma includes a light emitting device, configured to emit a light beam into the plasma, along an axis. In addition, the apparatus includes a collector configured to collect the Thomson scattering from the plasma at an angle less than 90 degrees from the axis of the light beam. Further, the apparatus includes a sensor assembly to detect the Thomson scattering.